NEW YORK — Who needs a doctor's note when you have permission to play hooky from Sean "P. Diddy" Combs?

"There is no work or school tomorrow. If you're tired, please leave immediately and let the thirsty people in," Diddy told the guests at his Lot 61 after-hours Grammy party around 3 a.m. Monday morning. "I don't think y'all understand — this ain't no regular after-Grammy party. This is an after-hours party. We're going 'til 7 a.m."

With Puff on the mic playing hype man and the DJ continually playing 50 Cent's "In Da Club," it seemed like everyone in the club was ready to stay up all night with the Bad Boy family. There were no blocked-off VIP sections, just some reserved seats for Puff's friends who put up huge box office, SoundScan and Nielsen ratings numbers.

Faith Evans and her husband moved from their table to join Puff's entourage, which included Loon, who had just come from the Neptunes bash across town. "Yo, the Neptunes' sh-- is ridiculous," Puff's potential next franchise player boasted. Like Loon, many of the partygoers had made earlier stops at jamborees hosted by Nelly and Justin Timberlake, Common and Erykah Badu, EMI Records, Fat Joe and Andre Harrell.

Fred Durst and a bopping Christian Slater held down one reserved booth, popping bottles with girls and a huge Asian bodyguard with sunglasses and fire engine red hair. TLC's T-Boz, who had complained about her feet hurting after walking the Grammy Awards' red carpet, was all rested up after skipping the actual show. She stood on the chair in her reserved booth, dancing and singing.

Backstreet Boy Kevin Richardson casually strolled the packed dance floor before being stopped by a big bootie girl who was all too willing to back that thang up. At first Kevin seemed a little hesitant, but with 50's voice telling everyone to party like it was their birthday, not even the smooth singer could resist the chance to partake in the revelry.

As the DJ segued from 50 to Nas, more people filed in. "They shootin' " Nas' voice said as Jay-Z, standing on his seat, bounced with a couple of girls on his left side and Dame Dash on his right. Dash bopped his head and chatted with a smiling Queen Latifah.

Even the humorously irritable Jack Osbourne didn't have any gripes as he sat in another part of the club with friends, drinking juice, taking in the atmosphere.

"Shout out to Jermaine Dupri and Janet Jackson, they're in the house," the DJ's regular hype man, Frank Jugga, told the crowd. "Shout out to Busta Rhymes, he's in the house. Shout out to Missy, I see you. Shout out to Jamie Foxx in the house."

Jugga would eventually have to give the mic back to P. Diddy. Although everyone was dancing and drinking, he wanted to make sure everyone knew why they were there.

"We're here to celebrate," P. said. "We're going to turn the lights on and see who's not dancing. We're going to get rid of all the riffraff who ain't dancing. This is a Bad Boy party, y'all. We're going to do this all night. Shout out to my man Vince Vaughn in the house."

As time drew closer to 5 a.m., people like Kimora Lee Simmons, Angie Stone and Blu Cantrell were making their exit, but Chilli and her man Usher seemed like they were just getting started.

"I said you wanna be startin' something, yeah, yeah," Usher sang as he danced to Michael Jackson's Thriller classic. Chilli looked like she was more partial to Bell Biv Devoe's "Poison" when it was played, and so did Diddy.

"Yeah, y'all! We just signed New Edition to Bad Boy. Shout out to the newest members of the family."

Even after most of the celebs had left, the night's biggest star was still going strong. "OK, we got all the riffraff outta here," Diddy said on the mic. "If you're tired, please go home. We are here to party; we might not never stop."